电解电容寿命与纹波电流测试

1、电解电容寿命纹波电流测试E-cap Lifetime Test1. 工作原理/ Working principle"200V50Hz仙）电路（b）uo的波形单相桥式整流电容滤波电路及稳态时的波形分析单相桥式幕流电容滤波电路及稳态时的波形分析 当U2为正半周并且数值大于电容两端电压Uc时，二极管D1和D3管导通，D2和D4管截止，电流一路流经负载电阻 RL，另一路对电容 C充电。当Uc>U2导致D1和D3管反向偏置而截止，电容通过负 载电阻RL放电，Uc按指数规律缓慢下降。 The diode D1&D3 work, D2&D4 cut off, the curr

2、e nt flows through the load resista nee RL in a loop andcharge the capacitor C up when U2 in the positive half circuit and its value exceeding the voltage Uc which is parallel conn ected in the two term in als of capacitor. Whe n Uc exceeds U2, and causes the diode D1&D3 cut off, the capacitor d

3、ischarge through the load resistance RL and Uc decline slowly according to the principle of in dex function. 当U2为负半周幅值变化到恰好大于Uc时，D2和D4因加正向电压变为导通状态，U2再次对C充电，Uc上升到U2的峰值后又开始下降；下降到一定数值时D2和D4变为截止，C对RL放电，Uc按指数规律下降；放电到一定数值时D1和D3变为导通，重复上述过程。 As the same reason , when U2 in the negative half circuit and the

4、amplitude is even changed to exceedUc ,the diode D2&D4 work due to the positive voltage and U2 charge capacitor C up aga in. Uc start todecline when it ' s voltage rise to the peak value of U2 and to a certain value , the diode D2&D4 cut off , the capacitor C discharge to RL, Uc decline

5、according to the principle of index function again. When the discharge to a certa in value, the diode D1&D3 work aga in and the cycle repeats.2. 测试方法/ Test Method2.1 测试温升计算电容寿命/ Life time of capacitor at testing temperature condition计算寿命公式/ Formula for calculat ing lifetimeE广一LX=L X 2 10 X2c T=

6、Kc*(Tc-Tx)适用公司/ Corporation suited : Feon、KSC、TL、TEAPO、CapXon说明/ Explanation :Lo:is operati ng life of capacita nee SPECTo： is SPEC temperature of capacitorTx:is capacitor ambie nt operati ng temperatureTc： is surface temperature of capacitor caseKc:is coefficie nt from table belowLx:useful life est

7、imati on2.2 测试纹波电流计算电容寿命/ Life time of capacitor at testing ripple current conditionLx=Lo*Kt*Kr计算寿命公式/ Formula for calculat ing lifetime(Kt=2A(To-Tx)/10 Kr=(5- t)/5 t=5*(Ix/Io)A2 )适用公司/ Corporation suited : HEC、JianghaiLo:is operati ng life of capacita nee SPECTo： is SPEC temperature of capacitorTx:

8、is capacitor ambie nt operati ng temperatureIx :is actual value of ripple currentIo:is specified ripple curre ntLx :useful life estimati on2.2.1 直接测量电容纹波电流/ Direct measure of E-cap ripple currentr.开关电路中电容纹波电流分析C1为buck电容，其充电时间受到低频交流输入影响，而放电时间则是受到开关管Q1的高频影响。即 A点受到低频交流输入影响，频率为交流频率的2倍，100Hz左右，故A点处所测试出电流

9、为电容 C1的低频纹波电流(IL) ； B点受到高频开关 Q1的影响，频率一般为 100KHz故B点所测试出的电流为电容 C1的高 频纹波电流(IH)。C1 is the buck capacitor, its charge time lies on the low freque ncy Vac in put, and the discharge time in flue need by the high freque ncy of switch ing MOSFET Q1. The freque ncy of positi on A, l ying on the Vac in put, is

10、 doubled, about 100Hz. And the curre nt flowed through just is the low freque ncy curre nt of C1; similarly, the freque ncy of positi on B, lying on the Q1, is about 100 KHz, and the curre nt is high freque ncy.目前我司对电容纹波计算方法定义为/The test method defined in our company at present is :血 Flj+阳 F)IIl:Low

11、frequency operating ripple current I L(low Freq) (A)IH：High frequency operating ripple current I H(low Freq) (A)F1:F :Coefficie nt for low freque ncy compe nsati onCoefficie nt for high freque ncy compe nsati onT :Coefficie nt for temperature compe nsati onLx: Actual curre nt2.2.2利用低通和高通滤波电路测量纹波电流/M

12、easurement via low pass or high pass filter对于输入大容量的电容，有低频（100HZ ）和高频（开关频率，如 100KHZ ）两种电流流过，电流的测 量必须串一个电流检测电阻去获得，而且低频纹波电流和高频纹波电流应分别测量。For bulk capacitor, both low freque ncy (100HZ) and high freque ncy (switch ing freque ncy, say 100 KHz) curre nt are flow ing. The curre nt shall be measured with a c

13、urre nt sense resistor. As the low and high freque ncy ripple shall be measured separately.RUicUo高通滤波电路低通滤波电路低通滤波电路的带宽为0wc（wc=1/RC），高频滤波电路带宽则为 >wc。The bandwidth of low pass filter is 0wc （ wc=1/RC） , and >wc in high pass filter. 在检测电阻上并接一个RC（ 1k5、0.1uF）电路，（如下图所示）用有效值表测量0.1uF两端的有效电压，即可得低频纹波电流值，

14、此时高频成分已被滤除。Add an RC (1K5, 0.1uF) across the sense resistor, measure rms voltage across 0.1uF; this will filter out thehigh freque ncy, leavi ng the 100Hz ripple curre nt.低频纹波电流测试图 在检测电阻上并接一个RC (O.luF、1K5)电路，(如下图所示)，用有效值表测1K5电阻两端的有效值电压，根据l=U/R即可获得高频纹波电流值，此时低频成分已被滤除。Add a CR (O.luF, 1K5) across the se